11i to r12 upgrade - do we really need to cancel requests or can we put them on hold?

In upgrade guide Release 11i to R12.2 (Part # E48834-02) on page 3-3 step 2 - Shut down application tier listeners and concurrent managers:

There is a statement - '

 

Navigate to Concurrent > Requests. In the Find Requests window, select All my

requests. Click Find, and click Cancel Pending requests as necessary."

Why can't we just put the pending jobs on hold? The majority of them are recurring ones that may or may not be a headache to reimplement, the 'on specific day' ones come to mind.